340ci vs 360ci engine

So should I get rid of the 318 right away? Or keep it put some mods in it and get some fun out of it. Say 350+ hp to get me going and to have some fun with. Then buy a 360? Or just do the full job on the 318 (or 360 which will get me even more hp) and keep it?

Heres the link to what im talking about:
http://www.moparmusclemagazine.com/techarticles/mopp_0409_318_engine_build/index.html
or
http://www.popularhotrodding.com/tech/0810phr_chrysler_318_engine/index.html